Select the most appropriate option to improve the underlined segment in the given sentence. If there is no need to improve it, select ‘No substitution required’.
A simple life of freedom and happiness is one of the more difficult thing to achieve.

Options

A. No substitution required
B. one of the most difiicult things to achieve.
C. one of the most difiicult thing to achieve.
D. one of the more difiicult things to achieve.

Answer

B

Explanation

one of the most difiicult things to achieve.